A typical wiring board includes a section of circuit board material (e.g., fiberglass, copper, vias, etc.) and circuit board components mounted to the electrical wiring board. Examples of circuit board components include integrated circuits (ICs), resistors, and inductors. Typically, circuit board components generate heat during operation. However, cooling by simple, un-enhanced natural convection, radiation and/or by heat conduction, is insufficient to keep junction temperatures below maximum operating limits.
Therefore, some ICs include heat sinks (e.g., a heat-spreader plate or cooling fins) to facilitate cooling. Heat sinks are thermally attached to the chips using a compliant (i.e., deformable) thermally conductive material. Conventional heat sinks maintain thermal contact with the corresponding circuit board component by being attached to the wiring board located adjacent to the IC component. Heat is removed from the cooling plate of the heat sink by methods such as forced air cooling and/or circulating liquid coolants. As the IC generates heat, heat flows from the IC package to the heat sink, and dissipates into the surrounding air. The fluid stream generated then carries the heat away, thus cooling the IC.
Another method for reducing excessive temperatures includes providing a low thermal resistance path between the circuit board components on the electrical wiring board and a primary heat sink structure. However, accumulation of tolerances in typical electronic assemblies can result in large differences in height between the top of the component and the heat sink. As such, it is often difficult to achieve a proper, reliable contact between surfaces to maintain mechanical compliance and a thermally conductive connection. Additionally, the two surfaces to be thermally connected may not be sufficiently parallel and in fact may shift relative to one another as the structure is transported, or thermally or mechanically stressed. These large stresses generated on the IC package increase the risk of IC failure. Therefore, height variations and misalignments may be compensated for by use of thermal gap fillers or thick layers of thermal grease, both of which have low thermal conductivity (e.g., 1-8 Watts per meter-Kelvin (W/m-K)). However, thick thermal gap fillers and thermal grease layers add considerable thermal resistance at the junctions, resulting in an increase in component temperatures. Furthermore, in practice, as the components shift, thermal grease may be squeezed out of the gaps between components resulting in wide fluctuations in thermal resistance.
Therefore, it would be desirable to have a low thermal resistance heat dissipation technique to accommodate for the variations and dynamics of individual components mounted on electrical wiring boards.